Near infrared absorbing fine particle dispersion liquid and method for producing the same, anti-counterfeit ink composition using near infrared absorbing fine particle dispersion liquid, and anti-counterfeit printed matter using near infrared absorbing fine particles

Abstract

Provided are a near infrared absorbing fine particle dispersion liquid having an absorption ability in a near infrared region, a clear contrast, and applicable to offset printing, and a method for producing the same, an anti-counterfeit ink composition using the near infrared absorbing fine particle dispersion liquid and an anti-counterfeit printed matter using near infrared absorbing fine particles. Also provided are a near infrared absorbing fine particle dispersion liquid containing a solvent of one or more kinds selected from vegetable oils or vegetable oil-derived compounds; near infrared absorbing fine particles in an amount of 2 mass % or more and 25 mass % or less, selected from one or more kinds of hexaboride fine particles expressed by a general formula XBa (wherein element X is at least one or more kinds selected from a group consisting of La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Y, Sm, Eu, Er, Tm, Yb, Lu, Sr, and Ca, satisfying 4.0≤a≤6.2); and a dispersant soluble in the solvent and having a fatty acid in its structure, wherein viscosity is 180 mPa/S or less, and an anti-counterfeit ink composition containing the near infrared absorbing fine particle dispersion liquid. Also provided is an anti-counterfeit printed matter excellent in anti-counterfeit effect due to the printed matter containing the near infrared absorbing fine particles.

The invention claimed is: 
     
       1. An anti-counterfeit ink composition for offset printing, comprising:
 a near infrared absorbing fine particle dispersion liquid, a resin varnish component, a vegetable oil component, a petroleum solvent component, and an additive agent, 
 wherein the near infrared absorbing fine particle dispersion liquid comprises
 a solvent of vegetable oils or vegetable oil-derived compounds; 
 near infrared absorbing fine particles of hexaboride fine particles expressed by a general formula XBa (wherein element X is at least one or more kinds selected from a group consisting of La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Y, Sm, Eu, Er, Tm, Yb, Lu, Sr, and Ca, satisfying 4.0≤a≤6.2); 
 a solvent of one or more kinds selected from the group consisting of alcohols, ethers, esters, ketones, and glycol ethers and having a boiling point of 180° C. or less; and 
 a dispersant which is soluble in the solvent of one or more kinds selected from the vegetable oils or vegetable oil-derived compounds and has a fatty acid in its structure, 
 
 wherein content of the solvent of one or more kinds selected from the group consisting of alcohols, ethers, esters, ketones, and glycol ethers is 0.0195 mass % or more and 1.0 mass % or less in the anti-counterfeit ink composition for offset printing. 
 
     
     
       2. The anti-counterfeit ink composition for offset printing according to  claim 1 ,
 wherein the dispersant is contained at 30 parts by weight or more and 200 parts by weight or less based on 100 parts by weight of the hexaboride fine particles. 
 
     
     
       3. The anti-counterfeit ink composition for offset printing according to  claim 2 , wherein an anchor portion of the dispersant has one or more kinds selected from the group consisting of a secondary amino group, a tertiary amino group, and a quaternary ammonium group. 
     
     
       4. The anti-counterfeit ink composition for offset printing according to  claim 2 , wherein the dispersant has an acid value of 1 mg KOH/g or more. 
     
     
       5. The anti-counterfeit ink composition for offset printing according to  claim 1 , wherein a dispersed particle size of the near infrared absorbing fine particles is 1 nm or more and 200 nm or less. 
     
     
       6. The anti-counterfeit ink composition for offset printing according to  claim 1 , wherein a lattice constant of the near infrared absorbing fine particles is 0.4100 nm or more and 0.4160 nm or less. 
     
     
       7. The anti-counterfeit ink composition for offset printing according to  claim 1 , wherein a surface of the near infrared absorbing fine particles is coated with a compound of one or more kinds selected from the group consisting of Si, Ti, Al, and Zr. 
     
     
       8. The anti-counterfeit ink composition for offset printing according to  claim 1 , wherein the vegetable oil is drying oil or semidrying oil. 
     
     
       9. The anti-counterfeit ink composition for offset printing according to  claim 1 , further comprising a pigment. 
     
     
       10. The anti-counterfeit ink composition for offset printing according to  claim 9 , wherein the pigment is an inorganic pigment, and is one or more kinds selected from the group consisting of carbon black, white pigment, an extender pigment, a red pigment, a yellow pigment, a green pigment, a blue pigment, a purple pigment, a fluorescent pigment, a temperature indicating pigment, a pearl pigment, and a metal powder pigment. 
     
     
       11. The anti-counterfeit ink composition for offset printing according to  claim 9 , wherein the pigment is an organic pigment and is one or more kinds selected from an azo lake pigment, an insoluble azo pigment, a condensed azo pigment, a phthalocyanine pigment, and a condensed polycyclic pigment. 
     
     
       12. The anti-counterfeit ink composition for offset printing according to  claim 1 , further comprising one or more kinds selected from the group consisting of a plasticizer, an antioxidant, a thickener, and a wax. 
     
     
       13. An anti-counterfeit printed matter, having a printed pattern on one side or both sides of a base material, wherein the printed pattern is printed by using the anti-counterfeit ink composition for offset printing of  claim 1  in an offset printing. 
     
     
       14. The anti-counterfeit printed matter according to  claim 13 , wherein the printed pattern further contains a pigment. 
     
     
       15. The anti-counterfeit printed matter according to  claim 14 , wherein the pigment is an inorganic pigment and is one or more kinds selected from the group consisting of carbon black, white pigment, an extender pigment, a red pigment, a yellow pigment, a green pigment, a blue pigment, a purple pigment, a fluorescent pigment, a temperature indicating pigment, a pearl pigment, and a metal powder pigment. 
     
     
       16. The anti-counterfeit printed matter according to  claim 14 , wherein the pigment is an organic pigment, and is one or more kinds selected from the group consisting of an azo lake pigment, an insoluble azo pigment, a condensed azo pigment, a phthalocyanine pigment, and a condensed polycyclic pigment. 
     
     
       17. The anti-counterfeit printed matter according to  claim 13 , wherein a value obtained by dividing an average value of a diffuse reflectance of the anti-counterfeit printed matter in a wavelength range of 800 nm to 1300 nm, by an average value of a diffuse reflectance of a blank not containing the near infrared absorbing fine particles in the wavelength range of 800 nm to 1300 nm, is 0.84 or less. 
     
     
       18. The anti-counterfeit ink composition for offset printing according to  claim 1 , wherein the solvent having the boiling point of 180° C. or less is one or more kinds selected from the group consisting of ethers, esters, and glycol ethers.